Chem 1 Lab Online Exam Study Guide PDF

[Chem 1 Lab Exam Study Guide ] The correct answer is in bold. Lab 1 Why is it dangerous to wear contact lenses in the lab? **Liquid can be trapped under them** The plastic reacts with acids Glasses protect better than lenses They don\'t protect well enough There are usually two different typ...

[Chem 1 Lab Exam Study Guide ] The correct answer is in bold. Lab 1 Why is it dangerous to wear contact lenses in the lab? **Liquid can be trapped under them** The plastic reacts with acids Glasses protect better than lenses They don\'t protect well enough There are usually two different types of fire extinguishers: CO2 based extinguishers and foam-based extinguishers. Never use a CO2 based extinguisher on a person. Do you know the reason why? **CO2 is freezing cold** CO2 is corrosive CO2 is toxic The person would suffocate What do you have to do before leaving the lab, to make sure you don't carry traces of chemicals outside? **Take off your lab coat and wash your hands** Wash your hands and then remove your lab coat Tell your supervisor Turn off the main power What is the first thing you have to do if there is a fire in the lab? **Alert people** Open the windows Splash the fire with water Run for the fire extinguisher Lab 2 What kind of phase change is happening to particles that transition from a solid to a gas state? **Sublimation** Condensation Evaporation Freezing What kind of phase change is happening to particles that transition from a gas to a solid state? **Deposition** Condensation Freezing Melting What kind of phase change is happening to particles that change from a gas to a liquid? **Condensation** Freezing Evaporation Melting Ethanol, like any physical material in this universe, is matter. Which of these is NOT a matter? **Light** Glass Bubbles Smokes Lab 3 To which of the three main chemical classes does Mercury (Hg) belong? **Metals** It\'s not an element in the periodic table Metalloids Non-metals What are the different colors caused by that we could see in the flame test? **Electrons falling back into their original shell** Metal ions reacting with chlorine Metal atoms reacting with oxygen in the air Electrons being excited Which groups of elements have a full octet of electrons? **Noble gases** Alkali metals Halogens Transition metals In the standard periodic table, the elements are listed in order of increasing atomic number Z. What do you think the atomic number represents? **Number of protons** Atomic Mass Number of electrons Number of neutrons Lab 4 Our control KCl showed high solubility in water. What does KCl actually stand for? **Potassium chloride** Kirchhoff\'s current law Potassium cyanide Kenny\'s cleaning detergent What happens when ionic compounds dissolve in water? **Cations and anions are released into the solution** They are transformed into non-metals They stick to the wall of the beaker They split up H2O molecules into H and O What's the charge of the K ion? **+1** -2 -1 +2 When K+ and Cl- forms an ionic bond\... **it\'s held together by electrostatic forces** potassium gains one electron and chlorine loses one electron potassium loses one electron and chlorine gains one electron potassium and chlorine share an electron pair Lab 5 Which are the subatomic particles of an atom? **protons - neutrons -- electrons** protons - neutrons -- orbitals protons - nucleus -- electrons protons - neutrons -- nucleus How many electrons are in the atom of Magnesium (Mg)? **12 electrons** 18 electrons 24 electrons 6 electrons What is the Atomic Number of Lithium? **3 as the number of protons** 1 the difference of neutrons and protons in the nucleus 4 as the number of neutrons 7 as the number of protons and neutrons in the nucleus How many protons does Potassium have? **19 protons** 13 protons 14 protons 20 protons Lab 6 Atoms and molecules are way too small to be seen, even with a microscope, so how can we count how many there is? **You count them by mass**. You count them using an electron microscope. You can\'t count atoms and molecules. You count them by volume. How many moles of AgNO3 silver nitrate should we use to be sure that we have excess, no matter which of the three compounds it is? **0.100 mol** 0.075 mol 0.050 mol 0.025 mol Lab 7 Why are only sterile pipette tips used in the lab? **To avoid contaminations of the sample** To prevent reproduction of proteins To make pipetting more precise To make sure that the tips can be reused Why did you press the plunger all the way down to the second stop of the pipet? **To push out the remaining fluid from the tip** To mix the contents in the tube To avoid contaminations To draw up liquid What do you need to do next before pipetting a different sample? **Discard the tip** Sterilize the pipette Discard the pipette Adjust the volume The Bradford assay only works at low protein concentrations (from 0.05 to 0.5 mg/mL protein). How can we reduce the concentration of protein in our sample? **Dilute the sample** Evaporate the sample Purify the sample Concentrate the sample Lab 8 What was the first step of using the balance, before adding anything to a weighing dish? **Tare the balance with the weighing dish on and the balance closed** Tare the balance with the weighing dish on and the balance open Tare the balance without a weighing dish and the balance closed Tare the balance without a weighing dish and the balance open What do you do if you add a bit too much solvent when filling the volumetric flask to the mark? **Start over, the solution cannot be saved** Use a distillation unit to evaporate the excess solvent Calculate the equivalent amount of salt and add that to the solution Remove the excess content of the flask until the volume matches the calibration mark Let\'s start by figuring out the amount needed in moles. From there, we can easily find the equivalent mass. Which equation do we need to find out how many moles of NH4Cl solution of it? **n = C x V** C = V / n n = C / V C = n x V How do we then get from moles (n) to mass (m)? **m = n x M** M = m x n m = M / n m = n / M Lab 9 What should we do to reduce the risk when working with high concentrated acid and base? **Dilute the acid** Never work with it Neutralize it Work in large volume The completion of acid-base titration is represented by end-point and equivalence point. What is end-point? **Point where the indicator changes color** Point where the neutralization reaction is complete Point where the number of moles of bases is equals to the number of moles of acid The theoretical completion of the reaction Lab 10 Based on your knowledge, which is the best definition for an acid? **Acids donate protons in aqueous solution** Acids split into two molecules in aqueous solution Acids remove a proton from each water molecule Acids accept protons from water molecules So what is the definition of a base? **Bases accept protons** Bases donate protons to water molecules Bases increase the number of protons in an aqueous solution Bases are proton donors What is the formula used to calculate the pH depending on the H+ concentration (\[H+ \])? **pH = - log (\[H+ \])** pH = log (1 x 107 ) pH = - log (1 x 107 ) pH = log (\[H+ \] x 10-7) How are the pOH and pH linked? **pH + pOH = 14** 7 + pOH = pH - 7 7 \* pH = 14 -- pOH pH = 7 + pOH